1. Field of the Invention
The present invention relates to 1-alkyl-3-aminoindazoles and preferably 1-(hydroxyalkyl)-3-aminoindazoles useful as intermediates for the preparation of 1-alkylindazoles. Use of the 1-alkyl-3-aminoindazoles as intermediates avoids unwanted side products and results in enantiomerically pure final pharmaceutically active products.
2. Description of the Related Art
Certain (aminoalkyl)indazoles are known to be useful for treating diseases of the central nervous system (WO 98/30548). WO 02/098861 A1 and WO 02/098862 A1 disclose methods of preparation of (aminoalkyl)indazoles. Specifically, these applications disclose the conversion of 2-(hydroxyalkyl)aminobenzaldehydes to 1-(hydroxyalkyl)indazoles, which are useful intermediates for the preparation of 1-(aminoalkyl)indazoles.
The following references generally describe 1-alkyl-3-aminoindazoles: U.S. Pat. Nos. 3,725,431, 3,681,382, 3,133,081; DE 2,248,175; Kawakubo et al. (1987); Vivona et al. (1979); Bouchet et al. (1980), Parnell (1959). Notably, Finch and Gschwend (1971) teach that nitrosation of 2-benzylaminobenzonitrile (N-benzylanthranilonitrile) followed by reduction produces the uncyclized hydrazino benzonitrile.
There is a need to provide further processes and intermediates to manufacture 1-(aminoalkyl)indazoles which avoid undesired isomers and which are capable of producing large quantities of the desired compound.
All patents, patent applications, and publications referenced in this application are incorporated in their entirety and form a part of the present application.